The police communicated the matter to the Foreign Regional Registration Office (FRRO), asking them to alert airport authorities so that the three suspects, believed to be JNU students, do not leave the country.

Following this, the look-out notice was issued yesterday, a police source said.

The three have been identified as the main conspirators in connection with the event, over which a case of sedition was registered and JNUSU president Kanhaiya Kumar was arrested, the source said.

The police tracked the youths' call details post February 9 till the day their phones were found to be switched off. Investigators have also recorded statements of more than a dozen JNU students who were witnesses, he said.

Meanwhile, the Special Cell has also been roped in in the ongoing search operation across cities. Police are looking out for 10 persons in connection with the event at JNU.